LEAVING WATER
(T58T6)
\
COOLER TUBE
INLET
CONNECTION
THERMISTOR..
ENTERING COOLER
WATER SENSOR
(T21
Fig. 4 - Cooler Sensor Locations
Bau’ The~~isfor ~ Thermistors
Code 68 and 69, Low Suction Superheat
Suction superheat is equal to 0°F (OOC) or the satu- rated suction is greater than 58 F (14.4 C) and either condition has been true for more than 5 minutes.
Possible causes for this failure are a stuck electronic expansion valve or thermistors
To reset, use the manual reset method.
Code 71 to 81, Thermistor Failure ~~~ If the measured temperature of a thermistor is less than
Thermistor Failure - A shorted or open circuit ther- mistor will cause the failure.
Wiving Failure - A shorted or open circuit will cause the failure.
P~oc~essnr Module Fczilure ~ If the circuitry in the pro- cessor module fails, the error could occur.
NOTE: The reset thermistor is an optional thermistor and is only used with outside or space temperature reset. It will only be read by the processor if the unit is con- figured for outside or space temperature reset.
The absence of a thermistor failure does not necessarily mean that a thermistor is accurate . To determine
accuracy, the reading must be compared with a measure- ment of the actual temperature to which the thermistor
probe is exposed.
Quick Test - The Quick Test feature allows the service technician to individually test all the inputs and outputs of the control system.
The test function operates the Quick Test diagnostic program. When the unit is in STANDBY mode, the test subfunctions will energize the solenoid valves, unloaders, electronic expansion valves and compressors. The solenoids and unloaders will energize for 3 minutes. The electronic expansion valve will travel to fully open in one test and to fully closed in the next. The compressors will energize for 10 seconds. The subfunctions are explained below. Refer to Table 6 for all the elements in the subfunctions.
NOTE: The Quick Test energizes the alarm light and alarm relay. They will remain energized as long as the unit is in Quick Test.
To reach a particular test, enter its subfunction number
and then scroll to the desired test with the + key. A 0
test can be terminated by pressing + . Pressing +
c lEl after a test has started will advance the system to the next test, whether the current one is operating or has timed out. Once in the next step, you may start the test
by pressing ENm or advance past it by pressing h .
c lc l While the unit is in Quick Test, you may access another display or function by depressing the appropriate keys; however, the unit will remain in the Quick Test func-
tion until T;;iH | is entered, or, if the keyboard is |
not used for 10 minutes, the unit will automatically leave the Quick Test function. See the following example:
14